It doesn’t get much clearer. The Earth’s climate is warming. Humans are the reason. But how many people are actually aware of the scientific consensus on this issue?

Research by Sander van der Linden and colleagues shows that when people believe that scientists overwhelmingly agree about climate change, they increase their a) own beliefs in climate change and b) beliefs that humans are responsible. They feel c) more worried about climate change, and as a result of a, b, and c, they support public action to mitigate the effects of climate change.

At the beginning of the study, participants indicated the percentage of scientists they thought agree on global warming and they answered some questions about their own climate change beliefs. People then received a message about scientific consensus, which took the form either of a) a simple description, b) a pie chart, or c) a metaphorical comparison related to trusting engineers’ consensus about bridges (i.e., if 97% of engineers agreed that a bridge was unsafe, would you use it?) or doctors’ consensus about illness. All the messages included the info that “97 % of climate scientists have concluded that human-caused climate change is happening.”

Then participants again indicated what percent of scientists they thought agree on global warming and answered questions about their own beliefs. All messages “worked,” in the sense that people perceived greater scientific agreement after the messages telling them that 97% of scientists agree than if they hadn’t read anything about the consensus at all (though the simple description and pie chart were more effective than the metaphor. People shifted their climate change beliefs more after encountering one of the more straightforward messages than the more complex metaphor. Great food for thought, as many science communicators insert metaphors wherever they can).

Of course, having people believe that there’s strong scientific consensus about climate is only one step toward the larger goal of having them endorse actions that mitigate the effects of climate change. But in follow-up analyses, the researchers identified that perceiving scientific agreement is a gateway belief: believing that scientists agree about global warming led to other beliefs, ones that get us closer to the goal of actions in favor of mitigating climate change. Specifically, it led to greater belief that climate change was real, human-caused, and worrisome. These beliefs, in turn, led to greater support for public action against climate change. It’s often hard to know what leads to what, especially when it comes to beliefs we keep hidden in our own heads, but with some semi-fancy math, these researchers quantified those relationships.

These studies have some clear takeaways for science communicators (especially when communicating about climate change — but maybe these ideas apply to other topics too — need more research!)

Emphasize scientific consensus, that an overwhelming percentage of scientists agree that climate change is a real problem caused by human activity.

Don’t worry so much about immediately pushing for public action against climate change. When people understand that scientists agree, they come to agree themselves that climate change is a problem that should be addressed, and THEN they come to support public action. Be careful about skipping steps.

At the same time, there’s not only one right way to communicate about climate change. There are truly effective ways, ineffective and potentially backfiring ways, and many in between. There aren’t cut-and-dry rules because every audience is unique, and taking the audience into account — their beliefs, values, and past experiences, for example — is crucial. But this work sheds light on communication strategies that are probably pretty far toward the “truly effective” end of the ways-to-communicate-climate-change continuum.